1. Field of Invention
The present invention relates to hypodermic needles, in particular to a shielded needle with an I.V. (intravenous) cannula.
2. Field of Prior-Art
In recent years concern has grown amongst hospital staff and health care workers regarding the possibility of getting accidentally stuck with a used hypodermic needle and thereby contracting an infectious disease, such as AIDS. Attempts have been made to design covers, guards, shields and the like for needles, particularly the type used for giving injections.
This form of needle is usually used once. Once the injection has been given, the needle can be placed out of reach of the patient, lessening one area of danger, i.e., the possibility of a mental patient attempting to inflict injury to nurse or doctor with the needle. However, the nurse or doctor can still be accidentally stuck with the needle.
Another problem concerning hypodermic needles occurs when the needle is being used to insert an I.V. cannula. This is because the cannula itself has to remain in the patient and be taped down, but the needle has to be withdrawn and thereby becomes unprotected and potentially dangerus since it can be a source of HIV infection if the user were to be accidentially stuck or pricked. The greatest danger occurs when the nurse or doctor is busy attaching the I.V. tubes to the cannula and securing the tube to the patient with tape; during this time the used and withdrawn hypodermic needle is exposed, unattended and therefore most dangerous. The needle is also exposed and dangerous before insertion.
Heretofore a number of solutions to these problems have been proposed, generally by shielding the hypodermic needle, particularly needles which are used once only for an injectable fluid.
T. Armao, in U.S. Pat. No. 3,134,380, dated May 26, 1964, shows a concertina-type cover which can be manually pulled forward to form a protective cover. Another embodiment in this patent is activated by a spring. However, unless there is sound structural support for the concertina covering, it does not provide a positive protection. Furthermore, no provision is made for use protecting an I.V. cannula inserter.
J. Kulli, in U.S. Pat. No. 4,747,831, dated May 31, 1988, shows a hollow handle which protects a needle and compression spring in the "rest" position. To prepare the needle for use as a cannula inserting needle, it has to be pushed forward so that the needle projects from the end of the handle. At this time the needle is exposed and potentially dangerous. An I.V. cannula can now be fitted over the needle and insertion carried out. A manually operated latch mechanism can now be used to release the needle, whereby the compressed spring carries the needle back into the handle to safety. The problem with this is that once the needle is protruding from the handle and is not shielded, it is dangerous.
V. Vaillancourt, in U.S. Pat. No. 4,725,267, dated Feb. 16, 1988, shows another concertina type cover which incorporates a hard cap which has an aperture at its center. When not in actual use the aperture is not aligned with the needle. However, when it is to be used for either an injection, or positioning an I.V. cannula, the cap's aperture is aligned and pushed down to the base of the syringe, thus exposing the needle. Once again we have an exposed and dangerous needle, especially while an I.V. cannula is being fitted.
J. Laico et al., in U.S. Pat. No. 4,892,521, dated Jan. 9, 1990, shows a cap of hard material covering a syringe needle and supported by guide rods. The cap includes an aperture which can be aligned manually with the needle when it is to be used. This method involves much manipulating around the needle's point with the fingers, which increases the chance of getting accidently stuck, rather than decreasing it.
P. Sudnak, in U.S. Pat. No. 4,894,055, dated Jan. 16, 1990, shows a two-cylinder, spring-activated telescopic arrangment covering the needle. It can be pushed down and locked in that position while the needle is in use, then reactivated after the needle is withdrawn. The problem with this method is that there are times when the needle is completely exposed, and this can happen after the needle has been used. Therefore it is dangerous.
L. Stern, in U.S. Pat. No. 4,900,311, dated Feb. 13, 1990, shows another spring-activated shield. It comprises an elliptical cross-sectioned syringe, having a hypodermic syringe needle attached and a spring-loaded elliptical sheath mounted axially around the syring's body and protruding sufficiently forward to cover the needle. To use, the sheath is pushed back along the shringe body after a cap has been removed from in front of the needle, which also provides an aperture through which the needle can protrude. After use the shield is manually replaced. Again this allows for an exposed needle, and finger manipulation around the needle. Therefore it presents a dangerous device.
F. DuPont, in U.S. Pat. No. 4,915,1990, dated Apr. 10, 1990, shows a needle and its shield within a cover box. When removed from the cover box and fitted onto a syringe, the needle is enclosed in a sheath which has solid end sections with an intermediate callapsible center portion, such that as the needle is injected into the patient the center portion collapses, and when the needle is withdrawn the center portion expands and re-covers the needle. While this may seem to be a well shielded needle, there is nothing to prevent the needle from sticking a nurse or doctor accidentally because the center portion is always able to collapse and allow the needle to penetrate.
T. Terndrup, in U.S. Pat. No. 4,917,672, dated Apr. 17, 1990, shows a shield sleeve covering the point of a hypodermic needle and held in place by a spring whose other end is attached to the syringe. The sleeve can be manipulated by hand to prevent or allow the needle's point to protrude through a hole in the sleeve's end for injection purposes. However, as the needle is being removed from the patient, the spring will automatically reposition the sleeve around and over the point in such a manner that the needle cannot again protrude unless again aligned by hand. No provision is provided for its use in placing an I.V. cannula. Also an I.V. cannula must be inserted at an acute angle to the patient's skin, yet this device must be used in a generally normal manner to the skin.
E. Larson, in U.S. Pat. No. 4,639,249, dated Jan. 27, 1987, shows a latch element which prevents movement of the syringe piston beyond a certain point. No teaching in this reference is directed toward needle protection.
P. Braginetz, in U.S. Pat. No. 4,666,435, dated May 19, 1987, shows an external shield which permits normal usage of the syringe for injection or withdrawing fluids, and which can then be moved into a non-usable locked position. The problem with this unit is that no automation is employed, also, until certain actions are carried out, the exposed needle is a danger.
J. Harbaugh, in U.S. Pat. No. 4,655,741, dated Apr. 7, 1987, shows a slidable cover which can be moved to various positions to cover or uncover the needle as required, This is done manually. No provision is provided to include placing an I.V. cannula in a patient.
C. Karemzer, in U.S. Pat. No. 4,795,432, dated Jan. 3, 1989, shows a flexible needle cover supported by an expanding spring arrangment which can be used to maintain a shield around the needle. However when inserting the needle in a patient, the shield automatically unlocks and allows the needle to be inserted. On withdrawing the needle, the spring automatically repositions the shield around the needle, and prevents subsequent use of the needle. No mention is made as to any possibility of using it for I.V. cannula insertion and the device could not be so used because its size and width will prevent this.
M. Milorad, in U.S. Pat. No. 4,702,739, dated Oct. 27, 1987, shows a slidable cylindrical needle shield, which can be used to both shield the needle and limit the needle's inward penetration, and can be manually extended to reshield the needle when it is withdrawn. The problem is the same as with Karezmer device in that the shield dimension prevents the needle being held almost parallel to the skin which is required to withdraw blood from peripheral veins or when inserting an I.V. cannula needle.
J. DeLuccia, in U.S. Pat. No. 4,675,005, dated Jun. 23, 1987, shows a sleeve enclosing a syringe unit and is locked to its proximal end. In use the syringe is unlocked and pushed forward toward the distal end, thereby exposing the needle and providing it to be used for an injection. Thereafter withdrawal it can be returned to the proximal end for relocking. The problem here again is that its bulk, which is unavoidable due to its construction, makes it unsuitable to be positioned at an acute angle to the patient's skin for insertion of an I.V. cannula needle. No mention is made for this use.
T. Haber, in U.S. Pat. No. 4,767,413, dated Aug. 30, 1988, shows a pull-back shield with self-locking catch pawls, such that the needle can be made to remain extended for administering dental injections, after which the pawls can be released to allow spring action to again extend the shield toward the distal end so as to provide a safe cover for the used needle. The problem here is that manipulation is required to make the used needle safe. No mention is made to use this unit to place an I.V.cannula.
The following patents also disclose various forms of needle protection:
Italian patent 704,152, dated Apr. 1966, R. Davis, U.S. Pat. No. 4,846,804, Mar. 24, 1988; D. Sitar, U.S. Pat. No. 4,846,805, Dec. 4, 1987; M. Glick, U.S. Pat. No. 4,863,436, Oct. 11, 1988; W. Bayless, U.S. Pat. No. 4,863,434, Jan. 9, 1988; M. Sturman, U.S. Pat. No. 4,863,435, filed Aug. 24 1988. However a problem which exists with the needles of all of these references is that automatic protection of the needle immediately after use is not provided.